The geometry of vector graphics artwork can be defined by bounded cubic Bezier curves. Traditional methods of coloring curves in such artwork is by fills and gradients. Simple coloring can be accomplished using solid fills. For richer coloring, axial and radial gradients can be used, where a user defines a set of color locations and associated color values. The value of a color at a pixel inside an artwork shape is then computed by interpolating between these color points in the direction of the gradient (e.g., axial or radial). However, the resulting coloring using fills and gradients may be limited in terms of complexity. Moreover, the coloring that is produced using fills and gradients is unrelated to or uncoupled from the topology of the shape that is being colored, which significantly limits the creativity and expressiveness of the user.
Diffusion curves provide a more complex and rich form of coloring vector graphics. Diffusion curves are vector graphic primitives for creating smooth-shaded images. Each diffusion curve partitions the geometric space through which it is drawn, defining different colors on either side of the curve. When rendered, these colors then spread into the regions on both sides of the curve in a way analogous to diffusion. The colors may also be defined to vary smoothly along the curve, and the sharpness of the color transition from one side of the curve to the other may also be specified. Even though diffusion curves offer a rich coloring model they are not intuitive to use, and it is difficult to control the color values at the time of creation. Furthermore, the use of diffusion curves necessitates a color being computed for every pixel of the artwork whenever a change in viewing aperture is made, which is computationally expensive.
In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be used, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. The aspects of the present disclosure, as generally described herein, and illustrated in the Figures, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are explicitly contemplated herein.